Continuous casting apparatus and method

ABSTRACT

A conveyor furnace system is provided that includes a housing, a conveyor, a vacuum device, and at least one heating element. The housing may have a first end and a second end. The conveyor may be configured to transit one or more component molds from the first end to the second end. The vacuum device may be configured to selectively produce a below atmospheric pressure within the housing. The at least one heating element may be disposed in the housing, and has a first end disposed adjacent the first end of the housing and a second end adjacent the second end of the housing. The at least one heating element is configured to provide a vertically tapered heating exposure in a direction from the first end of the housing to the second end of the housing.

BACKGROUND OF THE INVENTION 1. Technical field

The present invention relates to component casting and more particularlybut not exclusively to apparatus and methods for casting ofdirectionally solidified components.

2. Background Information

It is known to use a casting process to produce a wide range ofcomponents with complex shapes that would be otherwise difficult oruneconomical to manufacture by other methods. Molten material is pouredinto a mold that defines the shape of the component. The material isthen allowed to cool and solidify in the shape of the mold. Where thematerial has a melting point well above standard ambient temperature andpressure (SATP) (which is typical for most metals), the pouring of themolten material takes place within a furnace. It is known to control thecooling of the molten material in the mold to control the microstructureof the solidified material.

It is known to provide multiple components simultaneously by arranging aplurality of molds in a single assembly. In some instances, the moldsmay be connected by a network of casting channels through which moltenmaterial from a casting cup can be fed to the multiple moldssimultaneously. Once filled, the molds are collectively drawn from thefurnace in a controlled manner.

For some components (e.g., gas turbine engine turbine blades), it isdesirable to produce the component as having a “single crystal”metallurgical microstructure. The term “single crystal” (sometimescalled a “monocrystalline”) refers to a solid material in which thecrystal lattice of the entire body of the material is continuous andunbroken to the edges of the body, with no grain boundaries. A singlecrystal metallurgical microstructure can be produced, for example,through a process typically referred to as “directional solidification”,wherein control is exerted over the nucleation and the growth of singlecrystals in a molten metal as it passes from its liquid state to a solidstate.

Techniques for producing single crystal components are well known. Anexample of such a technique is a Bridgman-Stockbarger technique. Withinthis technique, a mold may contain a seed crystal to initiate a singlegrain or crystal growth and is gradually withdrawn from the furnace in adirection opposite to that of the desired crystal growth such that thetemperature gradient within the molten material is effectivelycontrolled.

FIG. 1 schematically shows a known apparatus for the simultaneousmanufacture of multiple cast components using a directionalsolidification process. As shown in the FIG. 1, the apparatus comprisesa pouring cup 1 into which molten material M is poured. A plurality offeed channels 2 extend radially around the centrally arranged cup 1 to atop end of the molds 3. Molten material M poured into the cup 1 flowsalong the feed channels 2 and into the molds 3. Each mold 3 may beprovided with a seed crystal 4 at a bottom end of the respective mold 3.Beneath the bottom end of the molds 3 is a chill plate 5 which isgenerally maintained at a temperature below the melting point of thematerial M, thereby enabling the creation of a temperature gradient fromthe bottom to the top of the molds 3. In most instances, the molds 3 aredisposed within a furnace having a heat source 6 disposed around theperiphery of the furnace. Thus, the heat source 6 encircles the pouringcup 1 and mold assembly. Once the molds 3 are filled with the moltenmaterial M, the mold assembly is moved vertically in a controlled manneraway from the heat source in the direction of arrow A to ensuredirectional solidification from the bottom of the molds 3 to the top ofthe molds 3. The controlled, directional cooling encourages thedirectional solidification process within the semi-molten casting.

This type of “batch” casting process possesses a number of differentchallenges. For example, in many applications a mold assembly configuredto produce a substantial number of components in a single batch is used.On the one hand, such a batch process may be efficient in terms of thenumber of components being cast. On the other hand, such a batch processrequires the components to be positioned at different positions withinthe furnace. Hence, the distance between respective components and theheat source almost always varies. As a result, within the batch,different components are subjected to different thermalenvironments/thermal gradients. The aforesaid differences within asingle batch can undesirably produce components having differentmetallurgical properties. In addition, in many instances the weight ofeach individual component mold (which molds are often combined into asingle structure) may be substantial when filled. After completion ofthe process, each filled mold must be removed from the batch device.This can present an ergonomic issue for the operator for those instanceswhen heavy components are being produced, or in those instances whenmultiple molds are configured together and the collective weight of thefilled molds is significant. Also, the inherent nature of the batchprocessing increases the risk of greater numbers of defectivecomponents; e.g., if a batch is not processed correctly, it is likelythat all of the components within the batch will be defective. Stillfurther, batch processing is time consuming. The batch device must beset up properly, the molds heated and filled, and then moved relative tothe heat source to produce the desired directional solidification. Oncethe directional solidification process is completed, then the entirestructure must be allowed to cool before an operator can access it.Hence, although there may be an efficiency gained in terms of being ableto process a number of components in a single batch, the aforesaidprocess is not efficient in terms of the amount of time required frombeginning to end.

What is needed is an apparatus and method that improves upon thepresently available devices and methodologies for producingdirectionally solidified components.

SUMMARY

According to an aspect of the present disclosure, a conveyor furnacesystem is provided that includes a housing, a conveyor, a vacuum device,and a plurality of heating elements. The housing has a first end and asecond end, and the second end is opposite the first end. The conveyoris configured to transit one or more component molds from the first endto the second end. Each component mold has a base end and a top end anda height extending therebetween. The vacuum device is configured toselectively produce a below atmospheric pressure within the housing. Theplurality of heating elements are disposed in the housing, and arearranged within the housing so that the one or more component moldstransiting through the housing are subjected to a progressivelydifferent heating exposure in a direction from the first end to thesecond end during operation of the system.

In any of the aspects or embodiments described above and herein, thehousing may include a loading station and an intermediate station, andthe conveyor may be configured to transit the one or more componentmolds from the loading station and into the intermediate station, andthe plurality of heating elements are disposed in the intermediatestation.

In any of the aspects or embodiments described above and herein, thehousing may include an unloading station, and the loading station isdisposed at the first end of the housing, and the unloading station isdisposed at the second end of the housing, and the intermediate stationis disposed between the first end and the second end.

In any of the aspects or embodiments described above and herein, theloading station, the intermediate station, and the unloading station maybe linearly arranged.

In any of the aspects or embodiments described above and herein, theloading station, the intermediate station, and the unloading station maybe non-linearly arranged.

In any of the aspects or embodiments described above and herein, thevacuum device may be configured to selectively produce a belowatmospheric pressure within the loading station, the unloading station,and the intermediate station, all independent from one another.

In any of the aspects or embodiments described above and herein, thehousing may include at least one station configured for loading andunloading component molds.

In any of the aspects or embodiments described above and herein, thehousing may include an intermediate station that extends arcuately fromthe at least one station, and the first end of the housing is disposedat the at least one station and the second end of the housing isdisposed at the at least one station.

In any of the aspects or embodiments described above and herein, theprogressively different heating exposure may continuously change in thedirection from the first end to the second end during operation of thesystem.

In any of the aspects or embodiments described above and herein, theprogressively different heating exposure may continuously decrease inthe direction from the first end to the second end during operation ofthe system.

In any of the aspects or embodiments described above and herein, theprogressively different heating exposure may change in a steppedconfiguration in the direction from the first end to the second endduring operation of the system.

In any of the aspects or embodiments described above and herein, thestepped configuration may include a plurality of steps, with eachdownstream step having a decreased heating exposure.

In any of the aspects or embodiments described above and herein, theconveyor furnace system may further include a plurality of coolingelements, and the plurality of cooling elements may be arranged withinthe housing relative to the plurality of heating elements so that theone or more component molds transiting through the housing are subjectedto a progressively different heating exposure in a direction from thefirst end to the second end during operation of the system.

According to another aspect of the present disclosure, a conveyorfurnace system is provided that includes a housing, a conveyor, a vacuumdevice, and at least one heating element. The housing may have a firstend and a second end, which second end is opposite the first end. Theconveyor may be configured to transit one or more component molds fromthe first end to the second end. Each component mold may have a base endand a top end and a height extending therebetween. The vacuum device maybe configured to selectively produce a below atmospheric pressure withinthe housing. The at least one heating element may be disposed in thehousing. The at least one heating element has a first end disposedadjacent the first end of the housing and a second end adjacent thesecond end of the housing. The at least one heating element isconfigured to provide a vertically tapered heating exposure in adirection from the first end of the housing to the second end of thehousing.

In any of the aspects or embodiments described above and herein, thefirst end of the heating element has a first vertical heating exposureportion, and the second end of the heating element having a secondvertical heating exposure portion, and the first vertical heatingexposure portion is greater than the second vertical heating exposureportion.

In any of the aspects or embodiments described above and herein, thefirst vertical heating exposure portion and the second vertical heatingexposure portion may both extend from adjacent a ceiling of the housing.

According to another aspect of the present disclosure, a method ofproducing a directionally solidified component is provided. The methodmay include: a) heating a component mold within a conveyor furnacesystem to a predetermined temperature, the conveyor furnace systemhaving a housing with a first lengthwise end and an opposite secondlengthwise end, and the component mold having a top vertical end and abottom vertical end; b) transferring a charge of molten metal into theheated component mold; c) transiting the heated component moldcontaining the charge of molten metal within the housing from the firstlengthwise end to the second lengthwise end; and d) exposing the heatedcomponent mold containing the charge of molten metal to a verticallytapered heating exposure in a direction from the first lengthwise end ofthe housing to the second lengthwise end of the housing.

In any of the aspects or embodiments described above and herein, themethod may further include selectively creating an environment withinthe housing that is below atmospheric pressure.

In any of the aspects or embodiments described above and herein, thehousing may include a loading station disposed at the first lengthwiseend of the housing and an unloading station disposed at the secondlengthwise end of the housing, and an intermediate station disposedbetween the loading station and the unloading station, and the methodmay further include loading the component mold into the loading stationprior to heating the component mold to the predetermined temperature,transiting the component mold from the loading station, through theintermediate station, and into the unloading station, and unloading thecomponent mold from the unloading station.

In any of the aspects or embodiments described above and herein, themethod may further include selectively creating an environment withinthe loading station that is below atmospheric pressure prior totransiting the component mold from the loading station, through theintermediate station, and into the unloading station.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a prior art batch-type apparatusfor producing directionally solidified components.

FIG. 2 is a diagrammatic cross-sectional view of a portion of a gasturbine engine.

FIG. 3 is a diagrammatic front view of a conveyor furnace embodiment.

FIG. 4 is a diagrammatic top view of the conveyor furnace embodimentshown in FIG. 3.

FIG. 5 is a diagrammatic view of a conveyor furnace embodiment.

FIG. 6 is a graph depicting percentage of component mold subjected to aheating element within the intermediate station versus distance traveledwithin the intermediate station.

FIG. 7 is a graph depicting percentage of component mold subjected to aheating element within the intermediate station versus distance traveledwithin the intermediate station.

FIG. 8 is a diagrammatic front view of a conveyor furnace embodiment.

FIG. 9 is a graph depicting percentage of component mold (from verticaltop) subjected to a heating element and/or a cooling element.

FIG. 10 is a diagrammatic front view of a conveyor furnace embodiment.

FIG. 11 is a diagrammatic front view of a conveyor furnace embodiment.

DETAILED DESCRIPTION

It is noted that various connections are set forth between elements inthe following description and in the drawings. It is noted that theseconnections are general and, unless specified otherwise, may be director indirect and that this specification is not intended to be limitingin this respect. A coupling between two or more entities may refer to adirect connection or an indirect connection. An indirect connection mayincorporate one or more intervening entities. It is further noted thatvarious method or process steps for embodiments of the presentdisclosure are described in the following description and drawings. Thedescription may present the method and/or process steps as a particularsequence. However, to the extent that the method or process does notrely on the particular order of steps set forth herein, the method orprocess should not be limited to the particular sequence of stepsdescribed. As one of ordinary skill in the art would appreciate, othersequences of steps may be possible. Therefore, the particular order ofthe steps set forth in the description should not be construed as alimitation.

The present disclosure is not limited to producing any particular typeof directionally solidified component. That said, there is particularadvantage to producing certain gas turbine engine components (e.g.,turbine blades) in a directionally solidified manner. To give anappreciation for such gas turbine engine components and the environmentin which they are utilized, a brief description of an exemplary gasturbine engine follows hereinafter. Referring to FIG. 2, a two-spoolturbofan type gas turbine engine 20 is shown (e.g., see FIG. 2). Thisexemplary embodiment of a gas turbine engine includes a fan section 22,a compressor section 24, a combustor section 26, and a turbine section28. The fan section 22 drives air along a bypass flow path B in a bypassduct, while the compressor section 24 drives air along a core flow pathC for compression and communication into the combustor section 26 thenexpansion through the turbine section 28.

The exemplary engine 20 shown in FIG. 1 includes a low speed spool 30and a high speed spool 32 mounted for rotation about an engine centrallongitudinal axis A relative to an engine static structure 36. The coreairflow is compressed by the low pressure compressor 44 then the highpressure compressor 52, mixed and burned with fuel in the combustor 56,then expanded over the high pressure turbine 54 and low pressure turbine46. The turbines 46, 54 rotationally drive the respective low speedspool 30 and high speed spool 32 in response to the expansion.

Core airflow increases in temperature as it travels through the engine.A variety of components that are exposed to high temperature air areoften cooled by lower temperature air (e.g., bypass air flow) passingthrough cooling passages or ducts formed within or between components.Many of these “cooled” components are produced by using a castingprocess, and include interior cavities for receiving cooling air.

Aspects of the present disclosure include a conveyor furnace system 60that includes a housing structure 62, one or more vacuum devices 64(e.g., a pump), a conveyor 66, one or more heating elements 68, and amaterial feed system 70. As will be described below, the conveyorfurnace system 60 is configured to have one or more component molds 78transit through the conveyor furnace system 60 from a first end to asecond end. Each component mold has a height that extends from a baseend 108 to a top end 110. Within the conveyor furnace system 60, thecomponent molds 78 are arranged so that the top end 110 of eachcomponent mold 78 is vertically above the base end 108. The presentdisclosure is not limited to any particular component mold 78configuration. An example of a component mold 78 configuration is oneconfigured to make a rotary blade for a gas turbine engine; e.g., aturbine blade. The present disclosure is not limited to any particulartype of component.

In some embodiments (e.g., see FIGS. 3 and 4), the housing structure 62includes a loading station 72, an unloading station 74, and anintermediate station 76 disposed there between. The embodiment showndiagrammatically in FIGS. 3 and 4 has a housing structure 62 having asubstantially straight line, linear configuration. The presentdisclosure is not limited to a substantially straight line, linearconfiguration. For example, in some embodiments, the housing structure62 may be arcuately shaped. An example of an arcuately shaped housingstructure 62 is a circular housing structure 62 (see FIG. 5). Somecircular housing structures 62 may combine the loading and unloadingstations 72, 74 into a single station. In such embodiments, the singleloading/unloading station would have the functionality described belowfor loading station 72 as well as the unloading station 74 unlessotherwise indicated below.

The loading station 72 is configured to include an operator access port77 (e.g., a door) that allows an operator to insert a component mold 78.The loading station 72 further includes a furnace port 80 that isconfigured to selectively provide an air pressure barrier (e.g., a door)between the loading station 72 and the intermediate station 76. Thefurnace port 80 is also configured to permit transfer of a componentmold 78 from the loading station 72 to the intermediate station 76 viathe conveyor 66. The access port 77 and the furnace port 80 areconfigured to be sufficiently air tight to allow the interior region ofthe loading station 72 to be maintained in a vacuum condition (e.g., ata pressure less than ambient) for an acceptable period of time; e.g., atleast the amount of time required to transfer the component mold 78 fromthe loading station 72 to the intermediate station 76 via the conveyor66. The loading station 72 is in communication with the one or morevacuum devices 64 to permit the loading station 72 to be evacuated tothe vacuum condition.

The material feed system 70 is configured to hold a charge of metalsufficient to fill a component mold 78. In some embodiments, thematerial feed system may include components located outside the housingstructure 62 and components located inside of the housing structure 62,or may reside completely within the housing structure 62. The materialfeed system 70 may be configured to heat a charge of metal into a moltenstate, or be configured to hold a charge of metal initially in a solidstate within the housing structure, wherein it will be heated into amolten state. The material feed system is configured to transfer themolten metal charge into a component mold 78 located within the housingstructure 62. At the time the molten metal charge is transferred to thecomponent mold 78, the component mold 78 is typically already heated toa casting process temperature. The present disclosure is not limited toany particular material feed system 70 configuration.

The unloading station 74 is configured to include an operator accessport 82 (e.g., a door) that allows an operator to remove a componentmold 78. The unloading station 74 further includes a furnace port 84that is configured to selectively provide an air pressure barrier (e.g.,a door) between the unloading station 74 and the intermediate station76. The furnace port 84 is also configured to permit transfer of acomponent mold 78 from the intermediate station 76 via the conveyor 66to the unloading station 74. The access port 82 and the furnace port 84are configured to be sufficiently air tight to allow the interior regionof the unloading station 74 to be maintained in a vacuum condition(e.g., at a pressure less than atmospheric) for an acceptable period oftime; e.g., at least the amount of time required to transfer thecomponent mold 78 from the intermediate station 76 via the conveyor 66to the unloading station 74. The unloading station 74 is incommunication with the one or more vacuum devices 64 to permit theunloading station 74 to be evacuated to the vacuum condition.

In those embodiments wherein the housing structure 62 is arcuatelyshaped and has a single loading and unloading station 72, 74 (e.g., anyshape that begins and ends at the single loading and unloading station72, 74), the single station may include an operator access port thatallows an operator to insert and remove a component mold 78 from thestation, a furnace inlet port that is configured to selectively providean air pressure barrier between the single station 74 and theintermediate station 76 (through which the conveyor may transitcomponent molds 78 into the intermediate station 76), and a furnace exitport that is configured to selectively provide an air pressure barrierbetween the single station 74 and the intermediate station 76 (throughwhich the conveyor may transit component molds 78 from the intermediatestation 76 and into the single station). As stated above, in suchembodiments, the single loading/unloading station would have thefunctionality described below for loading station 72 as well as theunloading station 74.

The at least one intermediate station 76 has a length 86, a width 88,and a height 90. Within the intermediate station 76, the housingstructure 62 may be described as having a base 92, a ceiling 94, a firstwidthwise wall 96, and a second widthwise wall 98. The height 90 may bedescribed as extending along a vertical axis (e.g., a gravitationalaxis), between the base 92 and the ceiling 94. The width 88 may beorthogonal to the length 86 and the height 90, extending between thefirst widthwise wall 96 and the second widthwise wall 98. The length 86extends from the loading station 72 to the unloading station 74. Thediagrammatic views of the housing structure 62 depict the intermediatestation 76 as having a rectangular cross-section. The intermediatestation 76 is not limited to a configuration having a rectangular shapedcross-section. The height 90 and the width 88 are configured to allow acomponent mold 78 to transit within the intermediate station 76 from theloading station 72 end to the unloading station 74 end. As will bedescribed below, the conveyor 66 runs in a lengthwise direction throughthe intermediate station 76. Hereinafter, component molds 78 transitingthrough the intermediate station 76 may be described in terms of“upstream” and “downstream”. If, for example, there is a first componentmold 78 and a second component mold 78 disposed within the intermediatestation 76, and the first component mold 78 is closer to the unloadingstation 74 than the second component mold 78, then the first componentmold 78 may be described as being “downstream” of the second componentmold 78. Conversely, the second component mold 78 may be described asbeing “upstream” of the first component mold 78. The intermediatestation 76 is configured to be sufficiently air tight to allow theinterior region of the intermediate station 76 to be maintained in avacuum condition (e.g., at a pressure less than atmospheric) for anacceptable period of time. In some embodiments, the intermediate station76 is in communication with the one or more vacuum devices 64 to permitthe intermediate station 76 to be evacuated to the vacuum condition.

The one or more heating elements 68 are disposed within the intermediatestation 76. In some embodiments, the one or more heating elements 68 maybe disposed adjacent the first widthwise wall 96 and adjacent the secondwidthwise wall 98.

The one or more heating elements 68 are arranged within the intermediatestation 76 so that the vertical height of a component mold 78 isprogressively subjected to a different heating exposure as the componentmold 78 transits through the intermediate station 76 in the directionfrom the loading station 72 to the unloading station 74. Referring toFIG. 3, the one or more heating elements 78 may be configured within thehousing structure 62 (e.g., within the intermediate station 76) to havea first end 73 disposed adjacent the first end of the housing structure62 (i.e., adjacent the loading station 72) and a second end 75 adjacentthe second end of the housing structure (i.e., adjacent the unloadingstation 74), wherein the one or more heating elements are configured toprovide a vertically tapered heating exposure in a direction from thefirst end of the housing structure 62 to the second end of the housingstructure 62. In some embodiments (e.g., see FIG. 3), the one or moreheating elements 68 may all extend from a position adjacent the ceiling94 of the housing, and the vertical length of the one or more heatingelement 68 decreases from the first end 73 of the heating elements tothe second end 75 of the heating elements 68.

The progressively changing heating exposure may be continuous orstepped. The term “continuous” refers to a heating exposure thatconstantly changes in the direction from the loading station 72 to theunloading station 74. The term “stepped” refers to a heating exposurethat has discrete levels of heating exposure in the direction from theloading station 72 to the unloading station 74. The present disclosureis not limited to either, and in some embodiments may include sectionsof continuous change and sections of stepped change. As an example of acontinuously changing heating element configuration (e.g., see FIG. 8),in the direction from the loading station 72 to the unloading station74, the heating exposure may be configured to change at a linear rate;e.g., X % of the vertical height of the component mold 78/unit transitdistance within the intermediate station 76 (e.g., see also FIG. 6).Alternatively, the change may be non-linear (e.g., see FIG. 7) whereinthere is a rate of change per unit distance (i.e., non-constant, but therate of change may vary at one or more positions between the loadingstation 72 and the unloading station 74).

As an example of a stepped heating element configuration, in an initialfirst transit distance “T1” of the intermediate station 76, 100% of thevertical height of the component mold 78 is subjected to the one or moreheating elements 68. As a result, 100% of the vertical height of therespective component mold 78 is subjected to an influx of thermal energyfrom the one or more heating elements 68. Within this initial firsttransit distance “T1” of the intermediate station 76, the heatingelements 68 may be aligned with 100% of the vertical height of thecomponent mold 78. In a second transit distance “T2” of the intermediatestation 76 immediately downstream of the first transit distance T1, thevertical top X % of the vertical height of the respective component mold78 (where “X” is an integer less than 100) is subjected to the one ormore heating elements 68. As a result, the vertical top X % of thevertical height of the respective component mold 78 is subjected to aninflux of thermal energy from the one or more heating elements 68.Within this second transit distance “T2” of the intermediate station 76,the heating elements 68 may be aligned with the vertical top X % of thevertical height of the respective component mold 78. In a third transitdistance T3 of the intermediate station 76 downstream of the secondtransit T2 (and therefore downstream of T1), the vertical top Y % of thevertical height of the respective component mold 78 (where “Y” is aninteger less than “X”) is subjected to the one or more heating elements68. As a result, the vertical top Y % of the vertical height of therespective component mold 78 is subjected to an influx of thermal energyfrom the one or more heating elements 68. Within this third transitdistance “T3” of the intermediate station 76, the heating elements 68may be aligned with the vertical top Y % of the vertical height of therespective component mold 78. The one or more heating elements 68 areconfigured in similar manner in each subsequent downstream transitdistance (e.g., T4, T5, T6, etc., each positioned to subject aprogressively smaller percentage of the respective component mold 78(determined from the vertical top of the component mold 78)) until theone or more heating elements 68 are not positioned to produce an influxof thermal energy at the rate delivered in the upstream transitdistances, or deliver any thermal energy influx at all. To facilitatethe explanation, FIG. 9 graphically illustrates 100% of the verticalheight of the respective component mold 78 being subjected to an influxof thermal energy from the one or more heating elements 68 for a transitdistance T1, 75% of the vertical height of the respective component mold78 being subjected to an influx of thermal energy from the one or moreheating elements 68 for a transit distance T2, 50% of the verticalheight of the respective component mold 78 being subjected to an influxof thermal energy from the one or more heating elements 68 for a transitdistance T3, 25% of the vertical height of the respective component mold78 being subjected to an influx of thermal energy from the one or moreheating elements 68 for a transit distance T4, and 0% of the verticalheight of the respective component mold 78 being subjected to an influxof thermal energy from the one or more heating elements 68 for a transitdistance T5, wherein transit distance T1 is closest to the loadingstation 72 end of the intermediate station 76, and T5 is closest to theunloading station 74 of the intermediate station 76. The percentagesdescribed above and shown within FIG. 9 are for explanation purposes,and the present disclosure is not limited thereto.

The present disclosure is not limited to any particular type of heatingelement 68. Examples of acceptable heating elements 68 include inductiontype heaters, or resistance type heaters or some combination thereof.

In some embodiments, the conveyor furnace system 60 may include one ormore cooling elements 100 in combination with the one or more heatingelements 68 (e.g., see FIG. 9). In these embodiments, the one or moreheating elements 68 and the one or more cooling elements 100 arearranged within the intermediate station 76 so that the vertical heightof a component mold 78 is progressively subjected to a different heatingexposure as the component mold 78 transits through the intermediatestation 76 in the direction from the loading station 72 to the unloadingstation 74. As described above, the progressively changing heatingexposure may be continuous or stepped; e.g., in a continuously changingheating element configuration, the heating exposure may be configured tochange at a continuous rate (e.g., linear or non-linear), and in astepped heating element configuration wherein the heating exposure isconfigured to change in discrete steps. In these embodiments wherein oneor more cooling elements 100 are utilized in combination with the one ormore heating elements 68, the one or more cooling elements 100 aredisposed to cool the portion of the vertical height of the componentmold 78 that is not subjected to an influx of thermal energy from theone or more heating elements 68. Using a stepped heating elementconfiguration as an example (see FIG. 9), in an initial first transitdistance “T1” of the intermediate station 76, 100% of the verticalheight of the component mold 78 is subjected to the one or more heatingelements 68, and zero percent of the component mold 78 is subjected tothe one or more cooling elements 100. In a second transit distance “T2”of the intermediate station 76 immediately downstream of the firsttransit distance T1, the vertical top 75% of the vertical height of therespective component mold 78 is subjected to the one or more heatingelements 68, and the vertical lower 25% of the vertical height of therespective component mold 78 is subjected to the one or more coolingelements 100. In a third transit distance T3 of the intermediate station76 downstream of the second transit distance T2, the vertical top 50% ofthe vertical height of the respective component mold 78 is subjected tothe one or more heating elements 68, and the vertical lower 50% of thevertical height of the respective component mold 78 is subjected to theone or more cooling elements 100. In a fourth transit distance T4 of theintermediate station 76 downstream of the third transit distance T3, thevertical top 25% of the vertical height of the respective component mold78 is subjected to the one or more heating elements 68, and the verticallower 75% of the vertical height of the respective component mold 78 issubjected to the one or more cooling elements 100. In a fifth transitdistance T5 of the intermediate station 76 downstream of the fourthtransit distance T4, none (e.g., 0%) of the vertical height of therespective component mold 78 is subjected to the one or more heatingelements 68, and all (e.g., 100%) of the vertical height of therespective component mold 78 is subjected to the one or more coolingelements 100. The above description is provided for explanatory purposesonly, and the present disclosure is not limited to the exemplarypercentages and transit distances. The similar configuration could beused for a conveyor furnace system 60 having one or more coolingelements 100 in combination with the one or more heating elements 68,wherein the progressively changing heating exposure is continuous; e.g.,the portion of the vertical height of the respective component mold 78not subjected to the one or more heating elements 68 may be subjected tothe one or more cooling elements 100.

Referring to FIG. 10, in some embodiments, the housing structure 62 mayinclude a plurality of thermal separators 102 disposed within theintermediate station 76. For example, in those embodiments having astepped heating element 68 configuration, a thermal separator 102 may bedisclosed between each thermal zone. Using the example provided aboveand diagrammatically shown in FIG. 10, a first thermal separator 102 maybe disposed at the lengthwise point within the intermediate station 76aligned with the end of the first transit distance “T1” and thebeginning of the second transit distance “T2”, and a second thermalseparator 102 may be disposed at the lengthwise point aligned with theend of the second transit distance “T2” and the beginning of the thirdtransit distance “T3”. FIG. 10 illustrates the likewise positioning of athird, fourth, and fifth thermal separator 102. The present disclosureis not, however, limited to vertically-oriented thermal separators 102,however. For example, in an alternative embodiment (e.g., see FIG. 11),a plurality of thermal separators 102 can be disposed to extendgenerally lengthwise, but skewed at an angle relative to the traveldirection of the component molds 78; e.g., oriented to extend generallyalong a line coincident with the vertically lowest segment of theheating elements 68 disposed within the intermediate station 76. Anon-limiting example of a thermal separator 102 is a curtain of carbonelements.

A conveyor 66 is configured to transit component molds 78 within theconveyor furnace system 60; e.g., from the loading station 72, throughthe intermediate station 76, to the unloading station 74. In someembodiments, the conveyor furnace system 60 may be configured in alinear (i.e., substantially straight) arrangement; e.g., the loadingstation 72 and the unloading station 74 are disposed at opposite ends ofthe intermediate station 76, and the loading station 72, intermediatestation 76, and unloading station 74 are in line with one another. Inthis configuration, the conveyor 66 is configured to transit componentmolds 78 from the loading station 72, through the intermediate station76, to the unloading station 74. The present disclosure is not limitedto any particular type of conveyor 66. An example of an acceptableconveyor is a “walking bridge” type conveyor. If a walking bridge typeconveyor is used, each component mold 78 may be connected to a copperblock that is configured to traverse along the walking conveyor.Elements of the walking bridge may be cooled to further heat transferfrom the component molds via the copper blocks. An alternative typeconveyor 66 may include structure for pushing the component molds 78(and copper blocks if attached) individually or collectively through thehousing structure 62. As a further alternative, the conveyor 66 may be aconfigured in a closed loop; e.g., where the conveyor 66 circles throughthe housing structure 62. The present disclosure is not, however,limited to a conveyor furnace system 60 having a linear configuration.In another non-limiting example, the conveyor furnace system 60 may havean arcuate configuration; e.g., an oval configuration, a circularconfiguration (see FIG. 5), etc. In any of the conveyor 66 embodiments,the conveyor 66 may be configured to rotate the component molds 78 asthey traverse through the intermediate station 76 to improve thetransfer of thermal energy to and from the component molds 78. In someembodiments, the conveyor 66 may be configured to alter the verticalposition of each component mold 78 as it progresses through theintermediate station 76; e.g., progressively drop the vertical positionof the component mold as it traverses through the intermediate station76. Changing the vertical position of a component mold 78 may be used asa means to alter the relative positions of the component mold 78 and therespective heating element 68, and thereby change the portion of thecomponent mold being subjected to an influx of thermal energy from theone or more heating elements 68 or subjected to cooling element 100.

In some embodiments, the one or more vacuum devices 64 may be a singlevacuum pump system with valving that permits evacuation of differentzones and subsequent maintenance of a vacuum condition (e.g., an airpressure lower than ambient). In this configuration, the loading station72 may be a first zone, the intermediate station 76 a second zone, andthe unloading station 74 a third zone, with the atmospheric pressure ineach zone independently controllable. In an alternative embodiment, theone or more vacuum devices 64 may include a vacuum pump system for eachzone that permits evacuation of the respective zone and subsequentmaintenance of a vacuum condition (e.g., an air pressure lower thanambient) within that respective zone. In some embodiments, the conveyorfurnace system 60 may include a source of inert gas that is configuredto provide inert gas into the intermediate station 76; e.g., directedonto defined sections of a component mold 78 for cooling or otherpurposes.

The conveyor furnace system 60 may include a control system 104configured to permit an operator to control operation of the conveyorfurnace system 60. The control system 104 may be in communication (e.g.,signal communication) with one or more of the one or more heatingelements 68, the conveyor 66, the one or more vacuum devices 64, thematerial feed system 70, the loading station 72, the unloading station74, sensors 106 (e.g., temperature sensors, pressure sensors, etc.), andother aspects of the conveyor furnace system 60. The control system 104may include any type of computing device, computational circuit, or anytype of process or processing circuit capable of executing a series ofinstructions that are stored in memory. The controller may includemultiple processors and/or multicore CPUs and may include any type ofprocessor, such as a microprocessor, digital signal processor,co-processors, a micro-controller, a microcomputer, a central processingunit, a field programmable gate array, a programmable logic device, astate machine, logic circuitry, analog circuitry, digital circuitry,etc., and any combination thereof. The instructions stored in memory mayrepresent one or more algorithms for controlling the aspects of theconveyor furnace system 60 (e.g., the heating elements 68, the vacuumdevices 64, the conveyor 66, etc.), and the stored instructions are notlimited to any particular form (e.g., program files, system data,buffers, drivers, utilities, system programs, etc.) provided they can beexecuted by the controller. The memory may be a non-transitory computerreadable storage medium configured to store instructions that whenexecuted by one or more processors, cause the one or more processors toperform or cause the performance of certain functions. The memory may bea single memory device or a plurality of memory devices. A memory devicemay include a storage area network, network attached storage, as well asa disk drive, a read-only memory, random access memory, volatile memory,non-volatile memory, static memory, dynamic memory, flash memory, cachememory, and/or any device that stores digital information. One skilledin the art will appreciate, based on a review of this disclosure, thatthe implementation of the control system 104 may be achieved via the useof hardware, software, firmware, or any combination thereof. The controlsystem 104 may also include input (e.g., a keyboard, a touch screen,etc.) and output devices (a monitor, sensor readouts, data ports, etc.)that enable the operator to input instructions, receive data, etc.

The following non-limiting method is an example of how the presentdisclosure may be implemented to produce a directionally solidifiedcomponent. The operator may insert at least one empty component mold 78within the loading station 72, and engage the same with the conveyor 66.The access port 82 and furnace port 80 of the loading station 72 areclosed to segregate the loading station 72. The one or more vacuumdevices 64 are operated (e.g., via operator input and instructions fromthe control system 104) to evacuate the loading station 72. In someembodiments, one or more heating elements 68 may be disposed in theloading station 72. In these embodiments, the one or more heatingelements 68 may be controlled (e.g., via operator input and/orinstructions from the control system 104) to heat the component mold 78up to a predetermined temperature (e.g., a casting process temperature)prior to the component mold being transferred to the intermediatestation 76. At the same time, or prior thereto, the one or more heatingelements 68 disposed within the intermediate station 76 are operated(e.g., via operator input and/or instructions from the control system104) to raise the temperature within the sections of the intermediatestation 76 to a predetermined temperature. In those embodiments thatinclude one or more cooling elements 100, the one or more coolingelements 100 may also be operated (e.g., via operator input and/orinstructions from the control system 104) to produce a region of lowertemperature relative to the higher temperature regions associated withthe one or more heating elements 68. The one or more vacuum devices 64are operated (e.g., via operator input and instructions from the controlsystem 104) to evacuate the intermediate station 76. Once the heatingelements 68 are at the requisite temperature and the intermediatestation 76 is evacuated, the furnace port 80 of the loading station 72may be opened (e.g., via operator input and/or instructions from thecontrol system 104) and the conveyor 66 activated to transfer the emptycomponent mold 78 from the loading station 72 to the intermediatestation 76. As indicated above, the material feed system 70 isconfigured to transfer a charge of molten metal sufficient to fill acomponent mold 78. The transfer of molten metal may occur within theloading station 72 or initially within the intermediate station 76. Thepresent disclosure is not limited to any particular material feed system70 configuration.

The conveyor 66 may be controlled to transit the now filled componentmold 78 through the intermediate station 76 in the direction from theloading station 72 end towards the unloading station 72 end. Theconveyor 66 may transit the filled component mold 78 through theintermediate station 76 at a constant or a variable rate, or in a stepfunction manner, or some combination thereof. As the filled componentmold 78 transits through the intermediate station 76, initially 100% ofthe vertical height of the component mold 78 is subjected to the thermalenergy from the one or more heating elements 68; e.g., located on bothwidthwise sides of the intermediate station 76. In those embodimentsthat include one or more cooling elements 100, initially none of thevertical height of filled component mold 78 is subjected to the one ormore cooling elements 100. As the filled component mold 78 continues itstransit through the intermediate station 76, an increasingly lesserportion of the filled component mold 78 (from the vertical top end) issubjected to thermal energy from the one or more heating elements 68.During this same phase of the transit through the intermediate station76, in those embodiments that include one or more cooling elements 100,an increasingly greater portion of the filled component mold 78 (fromthe vertical bottom end) is subjected to the one or more coolingelements 100. As the filled component mold 78 approaches the unloadingstation 74 end of the intermediate station 76, none of the verticalheight of filled component mold 78 is subjected to thermal energy fromthe one or more heating elements 68. During this same phase, in thoseembodiments that include one or more cooling elements 100, 100% of thefilled component mold 78 is subjected to the one or more coolingelements 100.

As the filled component mold 78 approaches the unloading station 74, orprior thereto, the access port 82 and furnace port 84 of the unloadingstation 74 may be closed to segregate the unloading station 74, and theone or more vacuum devices 64 are operated (e.g., via operator input andinstructions from the control system 104) to evacuate the unloadingstation 74. Once the unloading station 74 is evacuated, the furnace port84 of the unloading station 74 may be opened (e.g., via operator inputand/or instructions from the control system 104) and the conveyor 66activated to transfer the filled component mold 78 from the intermediatestation 76 to the unloading station 74. The furnace port 84 of theunloading station 74 is subsequently closed, and the one or more vacuumdevices 64 (or other valving) are operated to return the unloadingstation 74 to an ambient pressure. The filled component mold 78 may thenbe removed from the unloading station 74 via the access door 82.

As stated above, in some embodiments, the conveyor furnace system 60 mayhave a circular housing structure 62 that utilizes a single structurethat is configured to function as both the loading and unloadingstations 72, 74. In such embodiments, the process described above mayremain essentially as described above, with the combinedloading/unloading station performing the described functions associatedwith loading empty component molds 78 and unloading filled and processedcomponent molds 78.

While various embodiments of the present disclosure have been disclosed,it will be apparent to those of ordinary skill in the art that many moreembodiments and implementations are possible within the scope of thepresent disclosure. For example, the present disclosure as describedherein includes several aspects and embodiments that include particularfeatures. Although these features may be described individually, it iswithin the scope of the present disclosure that some or all of thesefeatures may be combined with any one of the aspects and remain withinthe scope of the present disclosure. Accordingly, the present disclosureis not to be restricted except in light of the attached claims and theirequivalents.

What is claimed is:
 1. A conveyor furnace system, comprising: a housinghaving a first end and a second end, the second end opposite the firstend; a conveyor configured to transit one or more component molds fromthe first end to the second end, each component mold having a base endand a top end and a height extending therebetween; a vacuum deviceconfigured to selectively produce a below atmospheric pressure withinthe housing; and a plurality of heating elements disposed in thehousing, the plurality of heating elements is arranged within thehousing so that the one or more component molds transiting through thehousing are subjected to a progressively different heating exposure in adirection from the first end to the second end during operation of thesystem.
 2. The system of claim 1, wherein the housing includes a loadingstation and an intermediate station, and the conveyor is configured totransit the one or more component molds from the loading station andinto the intermediate station, and the plurality of heating elements aredisposed in the intermediate station.
 3. The system of claim 2, whereinthe housing includes an unloading station, and the loading station isdisposed at the first end of the housing, and the unloading station isdisposed at the second end of the housing, and the intermediate stationis disposed between the first end and the second end.
 4. The system ofclaim 3, wherein the loading station, the intermediate station, and theunloading station are linearly arranged.
 5. The system of claim 3,wherein the loading station, the intermediate station, and the unloadingstation are non-linearly arranged.
 6. The system of claim 5, wherein thevacuum device is configured to selectively produce a below atmosphericpressure within the loading station, the unloading station, and theintermediate station, all independent from one another.
 7. The system ofclaim 1, wherein the housing includes at least one station configuredfor loading and unloading component molds.
 8. The system of claim 7,wherein the housing includes an intermediate station that extendsarcuately from the at least one station, and the first end of thehousing is disposed at the at least one station and the second end ofthe housing is disposed at the at least one station.
 9. The system ofclaim 1, wherein the progressively different heating exposurecontinuously changes in the direction from the first end to the secondend during operation of the system.
 10. The system of claim 9, whereinthe progressively different heating exposure continuously decreases inthe direction from the first end to the second end during operation ofthe system.
 11. The system of claim 1, wherein the progressivelydifferent heating exposure changes in a stepped configuration in thedirection from the first end to the second end during operation of thesystem.
 12. The system of claim 11, wherein the stepped configurationincludes a plurality of steps, with each downstream step having adecreased heating exposure.
 13. The system of claim 1, furthercomprising a plurality of cooling elements, and the plurality of coolingelements is arranged within the housing relative to the plurality ofheating elements so that the one or more component molds transitingthrough the housing are subjected to a progressively different heatingexposure in a direction from the first end to the second end duringoperation of the system.
 14. A conveyor furnace system, comprising: ahousing having a first end and a second end, the second end opposite thefirst end; a conveyor configured to transit one or more component moldsfrom the first end to the second end, each component mold having a baseend and a top end and a height extending therebetween; a vacuum deviceconfigured to selectively produce a below atmospheric pressure withinthe housing; and at least one heating element disposed in the housing,the at least one heating element has a first end disposed adjacent thefirst end of the housing and a second end adjacent the second end of thehousing, wherein the at least one heating element is configured toprovide a vertically tapered heating exposure in a direction from thefirst end of the housing to the second end of the housing.
 15. Thesystem of claim 14, wherein the first end of the heating element has afirst vertical heating exposure portion, and the second end of theheating element having a second vertical heating exposure portion, andthe first vertical heating exposure portion is greater than the secondvertical heating exposure portion.
 16. The system of claim 15, whereinthe first vertical heating exposure portion and the second verticalheating exposure portion both extend from adjacent a ceiling of thehousing.
 17. A method of producing a directionally solidified component,comprising: heating a component mold within a conveyor furnace system toa predetermined temperature, the conveyor furnace system having ahousing with a first lengthwise end and an opposite second lengthwiseend, and the component mold having a top vertical end and a bottomvertical end; transferring a charge of molten metal into the heatedcomponent mold; transiting the heated component mold containing thecharge of molten metal within the housing from the first lengthwise endto the second lengthwise end; and exposing the heated component moldcontaining the charge of molten metal to a vertically tapered heatingexposure in a direction from the first lengthwise end of the housing tothe second lengthwise end of the housing.
 18. The method of claim 17,further comprising selectively creating an environment within thehousing that is below atmospheric pressure.
 19. The method of claim 18,wherein the housing includes a loading station disposed at the firstlengthwise end of the housing and an unloading station disposed at thesecond lengthwise end of the housing, and an intermediate stationdisposed between the loading station and the unloading station; themethod further comprising loading the component mold into the loadingstation prior to heating the component mold to the predeterminedtemperature, transiting the component mold from the loading station,through the intermediate station, and into the unloading station, andunloading the component mold from the unloading station.
 20. The methodof claim 19, further comprising selectively creating an environmentwithin the loading station that is below atmospheric pressure prior totransiting the component mold from the loading station, through theintermediate station, and into the unloading station.